Device for controlling temperaturess in fluid heating apparatus



K. BAUMANN 2,116,424

DEVICE FOR CONTROLLING TEMPERATURES IN FLUID HEATING APPARATUS May 3, 1938,

Filed Feb. 1, 1955 4 Sheets-Sheet l Inventor H6 Karl Baumann, by Wan 1 is A torney- M y 1933- A K. BAUMANN 2,116,424

DEVICE FOR CONTROLLING TEMPERATURES IN FLUID HEATING APPARATUS Filed Feb. 1, 1955 4 Shee ts-Sheet 2 Inventor Karl Baum'ann,

by 5 Hu K His Attorney.

May 3, 1938. K. BAUMANN DEVICE FOR CONTRQLLEING TEMPERATURES IN FLUID HEATING APPARATUS Filed Feb. 1, 1935 4 Sheets-Sheet 3 20 C/ I \c/- Invehtor Karl Baumann,

His ttor 'ney.

May 3, 1938- K. BAUMANN 2,116,424

DEVICE FOR CONTROLLING TEMPERATURES IN FLUID HEATING APPARATUS Filed Feb. 1, 1955 4 Sheets-Sheet 4 Rasponsive f H 51:35: of a P ime n laver Karl Baurnann,

by 7 E, His Attorney.

Patented no 3,1938 a a 2,116,424

UNITED STATES PATENT OFFICE:

DEVICE FOR CONTROLLING TEMPERA- a Tunas INFLUID HEATING Arman-laps Karl Baumann, Wilmslow, England, assignmto General Electric Company, a corporation of New York p Application February 1,1935, Serial No. use In Great Britain February 10, 1934 4 Claims. (c 236-20) This invention relates to fluid heating plant already explained; continue to change after it has and has for its object to provide improved means reached the required value.

for automatically controlling the action orthe Any change in the temperature at the outlet plant so as to maintain an operation factor may therefore cause protracted hunting of the 5 such as temperature at a predetermined level incontrolling apparatus. 5 dependently oi the load or other imposed external According to the present invention therefore conditions.' The invention has particular reierin order to reduce or eliminate such hunting in a ence to plant in which the point in the fluid path fluid heating plant, wherein the temperature of at which the control action can be conveniently the flu d at a de e Po in t ci t l5 l0 exerted is somewhat remote from the point at regulated by exerting a controlling action at anwhich the conditions are to be regulated .and in o e Point n the fluid circuit relatively remote which the intervening plant has an appreciable from the first point the con o action is reguheat capacity, For example, in th case of latedin accordance with the state of the fluid steam generating plant in which it is desired to a third p t h the circuit which sp maintain the temperature at the outlet constant more q y to a change in the c ntrol action 15 the temperature may b tr ll d i a i u ways than said first point and such regulation is modi- Ior instance by controlling the admission of the fled in accordance with the temperature at th heating medium or by cooling theheated fluid first point- In app y the v ion for inby injecting a cold fluid or by cooling the heated stance to the control of the outlet temperature of fluid by heat exchange with a cold fluid taking a steamgenerating' p fl means of a contro 20 place in a heahexchanger. In all such cases the acticnfhavihg efiect at a po t wh ch is located actual point in the fluid circuit at which th earlier in the fluid circuit that is nearer to the trol means must be located is somewhat remote ihletthe control action will be regulated in acfrom the outlet and consequently a certain time cordance With the State 01 the Steam t n inte is necessary ior the fluid to travel from the conmedicte Point in the fl circuit relatively nearto 25 trolling means to the outlet, I t ddit t the point atwhich the control action is exerted heating elements through whiohth fluid ha t and such regulation of the control action will be pass on itsway to the outlet may have a considermodified in acccldeli'lce with the temperature o able heat storage capacity some of. which may be the Steam at the Outlet so due to other parts of the installation. 1 In carrying utt v fluid l t r ula- As a result the temperature at the outlet will tors may conveniently be p oyed. A fluid j not immediately respond t th action of the onregulator comprises essentially a liquid containtrol and there may be considerable delay between ing system pp ed With liquid under. a Substanthe moment when the controlling impulses from tially cchstaht head d Pro ided with a nozzle the temperature responsive means at the outlet is through which the liquid is extruded n a let- A 35 originated and the moment when as a result of Pad mounted on pivoted arm acts as a/trget the action of the controlmeans the temperature for the jet of liquid and the arm is positioned: at the outlet has been brought back to the about its pivot by a temperature (or pressure) quired vahm, 'During the whole time until the responsive device so that the distance of the pad 40 temperature has been brought back to the from the nozzle is varied in accordance with the 40 quired value controlling impulsesof the original temperature (or Pressman The positioning kind will continue to be transmitted to the conthe pad m'tum cfmtrols the pressure in the trol means from the temperature responsive systemlin the nelghbourhood of the nozzle and l means at theoutlet with the result that the temthus regulates F actuated by the perature changeat the outlet will continue in pressure the Hqmd' An exampleof fluid jet 4 the same" direction after it has reached the reig g gig fi if the Area regulator I quired value until the effect oi the opposite kind undegtoii g f z gsfi on g a g g of impulses, which willbegin to be transmitted now ma 9 0 t e l v accompanying drawings which illustrate diaflfom the Outlet at moment h grammatically ways of applying the invention to perature starts to dlfier from the required value the regulation of t temperature f a steam in the opposite sense is felt. From this moment generating plant, l l

the steam temperature atthe outlet will begin to Figures 1 to 4 show the relative positioning" of.

change in the reverse direction but owing to the the control components as applied respectively, to

l inherent storage capacity of the system it will, as different methods of temperature control.

Fig. shows the arrangement of a temperature responsive fiuid Jet regulator.

Figs. 6 to show lay-outs of various forms of control apparatus embodying fluid jet regulators.

Referring first of all to Figs. 1 to 4, A is the 'flrst point, i. e. that at which it is desired to regulate the temperature, and B is the point at which the actual control action is exerted. Since in systems to which the invention is applicable the points A and B are relatively far apart the control action at B is regulated by temperature responsive means located at a third point C where the change in the condition of the fluid responds more rapidly to a change in the control action and this regulation is in turn modified by temperature responsive means located at the point A. It has been explained above that if the control Organs at the point B were regulated directly by temperature responsive means located at the point A there would be a liability to hunting owing to the time taken by the fluid in passing from the point in the fluid circuit at which the control action at B has efl'ect to the point A also on account oi the heat storage capacity of the. intervening path. Regulation of the control action in accordance with the temperature at the point C may be arranged to eliminate the hunting but it is necessary to modify the regulating efl'ect in accordance with the temperature at the point A since it is the temperature at this point which it is desired to control. a

In many cases there will be an approximately predeterminable relationship between the temperature at the pdnt C and the temperature at the point A. This relationship will depend upon various factors and principally upon the load and the position of the control organs and .this relationship may be utilized in eflecting the control. According to the arrangement'shown in Fig. 1 the fluid path is indicated by the reference I, while 2 indicates the flue passage or heating chamber in which the fluid system is heated. The point A is shown at the outlet of the fluid path and the control organs at the point B control the heating medium. As shown they consist of a damper controlling the flow of hot gases to the fluid system Alternatively in cases where gas or oil burners are employed they might comprise a control acting on the burner or on the gas or oil supply. It will be appreciated that whilst the system of control organs at B will afl'ect the whole of the fluid system the latter will respond more quickly at earlier points in its path than at later points. This is in part due to the fact that points lying earlier in the fluid path also he earlier in the path of the hot gases. Thus the control C is selected at a position located appreciably earlier in the fluid path than is the point A.

Fig. 2 shows an arrangement in which a bypass I is provided around the earlier path of the fluid circuit and control organs B comprise a cock controlling the bypass. Here the main point at which the control has efl'ect is that at which the bypass rejoins the main fluid path and hence the point C is located relatively soon after this point.

Fig. 3 shows an arrangement in which the fluid path consists for instance of superheaters 4 and i and the fluid path between these superheaters comprises a desuperheater 6 the action of which is controlled for instance as shown by throttling the steam outlet. The throttle will hence constitute the control organs B and its effect will be felt in the portion of fluid path located in the desuperheater 6. Here again the point C is preferis projected against a pad l3.

ably located between the outlet from the desuperheater and the superheater 5.

Fig. 4 shows an arrangement similar to that shown in Fig. 3 but in which the steam passing between superheaters 4 and 5 passes through a chamber 1 into which cold water is sprayed from a nozzle 8. Here the control B may as shown comprise a cock controlling the flow to the nozzle.

Fig. 5 illustrates diagrammatically the mode of operation of a fluid let regulator of the well known-Area type which is adapted for temperature regulation. The device essentially relies upon the action of a liquid, which is usually water, under pressure, in a conduit system 9 upon a piston or diaphragm III of a hydraulic motor connected to actuate control means. A conduit system as shown at I in Fig. 1 is supplied with liquid under'a constant head from a nozzle H and is in turn provided with a nozzle I! from which the liquid emerges in the form of a jet and The pad I3 is carried on a rocker arm I which is fulcrumed at l5 and-which, at the point I6 is acted upon by a rod I! connected at its further end with a tube I 8 of material possessing a relatively high co-eiflciency of expansion. This tube will constitute the temperature means and will be located at the point in the fluid circuit from which it is desired that the controlling impulse should originate. Thus a rise in temperature will cause the tube It to expand; this will lower the rod i1 and hence the point of support it of the arm I and in so-doing will move the pad l3 nearer to the nozzle ii. The pad will exert an increased reaction to the jet and hence raise the pressure in the conduit system 9 which increased pressure will by acting on the piston or diaphragm it cause a regulating impulse to be transmitted to the controlling apparatus. Conversely a fall in temperature will cause the support It to rise and move the pad it away from the nozzle l2 and so lower the pressure in the conduit system 9.

Obviously the relative positions of the pivot point and the point It at which the temperature responsive device acts are interchangeable provided the apparatus is so arranged that the correct control action is obtained.

Since the water is supplied to the conduit systems from a source of constant head it follows that the pressure in the conduit system is a deflnite function of the distance of the pad from the nozzle.

Fig. 6 shows a layout of a simple form of control apparatus embodying the invention in which two such regulators C and A are employed, the piston or diaphragm lflC of regulator C being connected to control organs i9 indicated as a throttle acting on the fluid circuit, it being intended that the control organs l9 should be located at the point B referred to in Figs. 1-4 and that the thermostats C and A should similarly be located at points in the fluid circuit corresponding to C and A (in Fig. 1) respectively. The conduit system A9 of the regulator A is connected to actuate bellows 20 operating on the pivot point Cli of regulator C. In this figure the parts of the regulators are referred to by the same references that are employed in Fig. 2 but prefixed by the letter A or C as the case may be. Thus the temperature responsive device Cl8 will exert a primary regulation on the control means by raising or lowering the pad C|3 in the manner above described while this action will be modifled by the action of the temperature responsive device All in raising or lowering the pivot point Cli.

e 3,110,424 Fig. '1 shows a modification of the arrangement 1 shown in Fig. 6 in which the primary control action exerted by the regulatorC is modified in the first place in accordance with the operating position of the control organs is. This is efi'ected by placing thepivot point Cl! on a beam 2| one end oi. which is supported by a bellows ill the pressure acting on which is controlled by the thermostat All as in the Fig. 6 arrangement, while the other end of the beam 2| is supported by a bellows 22 the pressure acting on which is that existing'in the conduit system C9. This is obtained by means of a connection 23 between the conduit system C9 and the bellows 22 the connection 23 containing an orifice or restriction 24 which restricts the rate oi" movement of fluid from the conduit 09 to the bellows 22. The control action exerted by the regulator C is then further modified by the control device A if the temperature at A has not been maintained constant by the two earlier control actions.

Fig. 8 shows an alternative arrangement to that shown in Fig. 7, in which a connection,

which may be made through a relay or may be a direct mechanical connection, as shown inthe figure, is made between the control organs I! and the beam CH of the regulator C through a spring 25, the movement of the control organs is varies the compression of the spring 25 and hence the resistance to movement offered to the arm C with the result that piston ill will move further than it would have moved it the upper support of the spring had been fixed. Again the final modification of the control will be obtained by means of the control devices A. In view of the over-regulation obtained by varying compression of the spring 25 this method of control is liable to become unstable and to overcome this instability various stabilizing means may be introduced, one of which is shown in Fig. 9, where a dashpot 26 and a further spring 25 is interposed between the spring 25 and the control lever C. In this arrangement spring 25 supplies a stabilizing force for rapid movements of piston Ill and the desired over-regulation will be obtained more slowly by spring 25 and dashpot Fig. 10 shows a further arrangement in which the primary control is obtained by means of a device responsive to the amount oi fluid passing through the system or to the load in the system. In the case of a steam power plant this may for instance, be the output from the prime mover. If a change in the load takes place an immediate adjustment of the control lever will take place by means'of the action of the bellows 21 operating against a spring 30, the position of which is therefore dependent on the load. The secondary adjustment of the control will in this case be obtained by means of the thermostat C and the final modification by means of the control organs A.

The temperature or pressure at the point A, to maintain which the control action is made. need not be an absolute temperature but may for instance be the temperature difierence between two points in the fluid circuit in which case the thermostat A might act differentially.

While in the descriptions given the controls are operated by means of bellows controlled by nozzles in accordance with designs used by Area, other well known devices may be used, such as electrical contacts and motors. Further additional power operated devices may be introduced to obtain more positive operation. Stabilizing means such as are shown in 9 item "may i also be introduced in any of the arrangements shown. Also instead oi. continuous operation,

intermittent operation may be employed by wellknown means providing impulses of constant or varying magnitude and at regular or varying intervals, the magnitude and/or the intervals being dependent on the departure of the actual temperaturesirom the desired temperatures and ii desired also on the rate oi change of temperatures.

. V I claim:-

.the valve, a conduit having a discharge nozzle for conducting operating fluid under pressure to the hydraulic motor, and means co-operatively associated with the male for controlling the fluid pressure in the motor, said means comprising a lever, a pad secured to the lever adjacent the nozzle, a device responsive to the temperature in the outlet of said heating coil, a pressure responsive element controlled by said temperature responsive device and forming a movable fuicrum for the lever, and another device responsive to the temperature at a point intermediate the inlet and the outlet of the coil and forming another movable fulcrum for the lever to modify the action of the first temperature responsive device.

2. In a fluid heating plant, the combination of a fluid circuit including a coil through which fluid to be heated is conducted during operation, means including a valve for controlling the heating of the fluid, a hydraulic motor for moving the valve, a conduit having a discharge nozzle for conducting operating fluid under pressure to the hydraulic motor, and means co-operatively associated with the nozzle for controlling the fluid pressure in the motor, said means comprising a first lever, a pad secured to the first lever adjacent the nozzle, a device responsive to the temperature in the outlet of the heating coil, a pressure responsive element controlled by the temperature responsive device, another pressure responsive device subject to the pressure in the motor, a, second 'lever connected to both pressure responsive elements and forming a movable fulcrum for the first lever, another temperature responsive device subject to the fluid temperature at a point intermediate the inlet and the outlet of the heating coil and forming another movable fulcrum for the first lever to modify the action nozzle, a device responsive to the temperature in v the outlet of said heating coil, 8. pressure responsive element controlled by said temperature responsive device and forming a movable fulcrum forthe lever, and another device responsive to the temperature at a point intermediate the inlet and the outlet of the coil and forming another movable fulcrum for the lever to modify the action of the first temperature responsive device, and means connected to the first lever for modifying the action of both temperature responsive devices in response to movement of the motor.

4. In a fluid heating plant, the combination of a fluid circuit including a coil through which fluid to be heated is conducted during operation, means including a valve for controlling the heating oi the fluid, a hydraulic motor for moving the valve, a conduit having a discharge nozzle for conducting operating fluid under pressure to the hydraulic motor, means co-operatively associated with the nozzle for controlling the fluid pressure in the motor, said means comprising a lever, a pad secured to the lever adjacent the nozzle, a

device responsive to the temperature in the outlet of said heating coil, a pressure responsive element controlled by said temperature responsive device and forming a movable fulcrum for the lever, and another device responsive to the temperature at a point intermediate the inlet and the outlet of the coil and forming another movable fulcrum for the lever to modify the action of the KARL BAUMANN. 

